Circuit component built-in module and method for producing the same

ABSTRACT

A circuit component built-in module of the present invention includes an insulating substrate formed of a mixture comprising 70 wt % to 95 wt % of an inorganic filler and a thermosetting resin, a plurality of wiring patterns formed on at least a principal plane of the insulating substrate, a circuit component arranged in an internal portion of the insulating substrate and electrically connected to the wiring patterns, and an inner via formed in the insulating substrate for electrically connecting the plurality of wiring patterns. Thus, a highly reliable circuit component built-in module having high-density circuit components can be obtained.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a circuit component built-in module. Inparticular, the present invention relates to a circuit componentbuilt-in module in which, for example, an active component is arrangedin an internal portion of an insulating substrate.

2. Description of the Prior Art

Recently, with a demand for high performance and miniaturization ofelectronic equipment, high-performance and high-density circuitcomponents have been increasingly desired. This leads to a demand for acircuit substrate commensurate with high-performance and high-densitycircuit components.

The formation of a multilayered circuit may be a solution to achievehigher-density circuit components. However, a conventional glass-epoxysubstrate requires a through-hole structure to form a multilayeredcircuit, to that is hardly a solution for high-density mounting.Therefore, a connection method using inner via holes that can connectbetween wiring patterns of LSIs or circuit components in the shortestdistance has been developed in various fields in order to achieve higherdensity packaging.

The connection method using inner via holes allows electrical connectiononly between the layers necessary to be connected through a connectioncalled an inner via, so that circuit components can be mounted with highdensity (U.S. Pat. No. 5,481,795, U.S. Pat. No. 5,484,647, and U.S. Pat.No. 5,652,042)

However, a substrate that has been conventionally used in the inner viaconnection comprises a resin based material, which has low thermalconductivity. Therefore, the problem of a low thermal conductivity isposed. In a circuit component built-in module, the higher densitymounting of circuit components leads to an increased demand forreleasing heat that has been generated in the components. However, theconventional substrate cannot sufficiently release heat, and therefore,the reliability of the circuit component built-in module deteriorates.

SUMMARY OF THE INVENTION

It is the object of the present invention to provide a highly reliablecircuit component built-in module in which circuit components aremounted with high density, and a method for producing the same.

A first circuit component built-in module of the present inventionincludes an insulating substrate formed of a mixture comprising 70 wt %to 95 wt % (on the basis of the mixture) of an inorganic filler and athermosetting resin; a plurality of wiring patterns formed on at least aprincipal plane of the insulating substrate (one wiring pattern consistsof a group of electric lines formed on the same plane); a circuitcomponent arranged in an internal portion of the insulating substrateand electrically connected to the wiring patterns; and an inner viaformed in the insulating substrate for electrically connecting theplurality of wiring patterns.

The first circuit component built-in module allows circuit components tobe mounted with high density, because the inner via formed in theinsulating substrate establishes inner-via-hole connection.

Furthermore, the first circuit component built-in module allows circuitcomponents to be mounted with further higher density by mounting circuitcomponents on the wiring patterns formed in an internal portion of theinsulating substrate.

Furthermore, the first circuit component built-in module constitutes ahighly reliable circuit component built-in module, because heatgenerated in the circuit components is released promptly by theinorganic filler.

Furthermore, the first circuit component built-in module allows the heatconductivity, the coefficient of linear expansion, the dielectricconstant, he breakdown voltage or the like of the insulating substrateto be changed in accordance with the circuit components by selecting asuitable inorganic filler. When the circuit component built-in moduleincludes a semiconductor device and a chip capacitor, noise in electricsignals can be reduced by reducing the distance between thesemiconductor device and the chip capacitor.

In one embodiment of the first circuit component built-in module, thewiring patterns are preferably formed on the principal plane and in aninternal portion of the insulating substrate. Mounting circuitcomponents on the wiring patterns formed in an internal portion of theinsulating substrate further increases the density in the circuitcomponents.

In one embodiment of the first circuit component built-in module, thecircuit component preferably includes an active component, and the innervia is preferably formed of a conductive resin composition. A circuitcomponent having a desired function can be formed by including an activecomponent in the circuit components. When the inner via is formed of aconductive resin composition, the production of the circuit componentbuilt-in module can be facilitated.

In one embodiment of the first circuit component built-in module, thecircuit component is preferably shielded from external air by theinsulating substrate. Shielding circuit components from external airprevents the reliability of the circuit components from deteriorating,which otherwise might deteriorate due to humidity.

In one embodiment of the first circuit component built-in module, thethermosetting resin preferably comprises at least one thermosettingresin selected from the group consisting of an epoxy resin, a phenolresin and a cyanate resin. These resins are excellent in heat resistanceand electrical insulation.

In one embodiment of the first circuit component built-in module, theinorganic filler comprises at least one inorganic filler selected fromthe group consisting of Al₂ O₃, MgO, BN, AlN and SiO₂. Use of theseinorganic filler provides an insulating substrate having an excellentheat dissipation. When MgO is used for the inorganic filler, thecoefficient of linear expansion of the insulating substrate can beraised. When SiO₂ (especially, amorphous SiO₂) is used for the inorganicfiller, the dielectric constant of the insulating substrate can bereduced. When BN is used for the inorganic filler, the coefficient oflinear expansion of the insulating substrate can be reduced.

In one embodiment of the first circuit component built-in module, anaverage particle diameter of the inorganic filler is preferably 0.1 μmto 100 μm.

In one embodiment of the first circuit component built-in module, thewiring patterns preferably comprise at least one conductive substanceselected from the group consisting of copper and a conductive resincomposition. Since copper has a small electrical resistance, fine wiringpatterns can be formed by using copper. Furthermore, electric lines canbe formed easily by using a conductive resin composition.

In one embodiment of the first circuit component built-in module, thewiring patterns preferably comprise lead frames formed by etching orstamping. The metal lead frame has a low electric resistance. Etchingallows the formation of fine wiring patterns. Stamping allows formationof the wiring patterns with simple equipment.

In one embodiment of the first circuit component built-in module, thecircuit component preferably comprises at least one component selectedfrom the group consisting of a chip resistor, a chip capacitor and achip inductor. A chip component can be readily buried in the insulatingsubstrate.

In one embodiment of the first circuit component built-in module,preferably, the mixture further comprises at least one additive selectedfrom the group consisting of a dispersant, a coloring agent, a couplingagent and a releasing agent. A dispersant serves to disperse theinorganic filler in the thermosetting resin uniformly and sufficiently.A coloring agent serves to color the insulating substrate, so that theheat dissipation of the circuit component built-in module can beimproved. A coupling agent serves to raise the adhesion between thethermosetting resin and the inorganic filler, so that the insulatingproperty of the insulating substrate can be improved. A releasing agentserves to improve the releasing property of the mold and the mixture, sothat the productivity can be raised.

In one embodiment of the first circuit component built-in module, theinsulating substrate preferably has a coefficient of linear expansion of8×10⁻⁶ /° C. to 20×10⁻⁶ /° C. and a heat conductivity of 1 w/mK to 10w/mK. A heat conductivity close to that of a ceramic substrate can beobtained, and a substrate having high heat dissipation can be obtained.

In one embodiment of the first circuit component built-in module, theactive component preferably comprises a semiconductor bare chip, and thesemiconductor bare chip is preferably flip-chip bonded onto the wiringpattern. The flip chip bonding of the semiconductor bare chip allowshigh density mounting of semiconductor devices.

In one embodiment of the first circuit component built-in module, theconductive resin composition preferably comprises, as a conductivecomponent, metal particles of at least one metal selected from the groupconsisting of gold, silver, copper and nickel, and an epoxy resin as aresin component. The above-listed metals have low electric resistances,and an epoxy resin is excellent in heat resistance and electricinsulation.

A first method for producing a circuit component built-in moduleincludes the following steps: processing a mixture comprising 70 wt % to95 wt % (on the basis of the mixture) of an inorganic filler and anuncured thermosetting resin into a first sheet having a through-hole;filling the through-hole with a thermosetting conductive substance so asto form a second sheet having the through-hole filled with thethermosetting conductive substance; mounting a circuit component on awiring pattern portion in a first film; positioning and superimposingthe second sheet on the side of the first film where the circuitcomponent is mounted, and superimposing a second film having a wiringpattern portion on the second sheet, thereby forming a third sheet inwhich the circuit component is buried; and heating the third sheet so asto form a fourth sheet in which the thermosetting resin and theconductive substance are cured.

According to the first method, the circuit component built-in module ofthe present invention can be produced easily.

A second method for producing a circuit component built-in module of thepresent invention is directed to a method for producing a circuitcomponent built-in module having a multilayered structure. The secondmethod includes the following steps: processing a mixture comprising 70wt % to 95 wt % (on the basis of the mixture) of an inorganic filler andan uncured thermosetting resin into a first sheet having a through-hole;filling the through-hole with a thermosetting conductive substance so asto form a second sheet having the through-hole filled with thethermosetting conductive substance; forming a wiring pattern on aprincipal plane of a release film and mounting a circuit component onthe wiring pattern; positioning and superimposing the second sheet onthe principal plane of the release film, and pressing the second sheettogether with the release film provided with the circuit component,thereby forming a third sheet in which the circuit component is buried;peeling the release film from the third sheet so as to form a fourthsheet; and positioning and superimposing a plurality of sheets producedin the same manner as the fourth sheet on one another with a filmincluding a wiring pattern portion on top of the plurality of sheets,and pressing and heating the plurality of sheets and the film, therebyforming a fifth sheet having a multilayered structure in which thethermosetting resin and the conductive substance are cured.

According to the second method, the circuit component built-in modulehaving a multilayered structure of the present invention can be producedeasily.

In one embodiment of the first and second methods for producing acircuit component built-in module, the circuit component preferablycomprises an active component, and the conductive substance comprises aconductive resin composition. A circuit component having a desiredfunction can be formed by including an active component in the circuitcomponents. Furthermore, when the conductive substance comprises aconductive resin composition, it is easy to fill a through-hole with theconductive substance and to cure the conductive substance. Therefore,the production is facilitated.

In one embodiment of the first and second methods for producing acircuit component built-in module, the first and second films are formedof copper foils, and the method further comprises the step of removingthe copper foil in a portion other than the wiring pattern portions soas to form wiring patterns after the step of forming a sheet in whichthe thermosetting resin and the conductive substance are cured. Thisstep facilitates the formation of the wiring pattern on the principalplane of the insulating substrate

In one embodiment of the first and second methods for producing acircuit component built-in module, the first and second films are formedof release films on one principal plane of which wiring patterns areformed, and the method further comprises the step of peeling the releasefilms from the sheet, after the step of forming a sheet having thethermosetting resin and the conductive substance cured. This stepfacilitates the formation of the wiring patterns on the principal planeof the insulating substrate.

In one embodiment of the first and second methods for producing acircuit component built-in module, the method further includes the stepof injecting a sealing resin between the copper foil or the wiringpattern and the circuit component after the step of mounting the circuitcomponent in the copper foil or the wiring pattern. This step preventsgaps from being formed between the circuit component and the wiringpattern, and strengthens the connection between the circuit componentand the wiring pattern.

In one embodiment of the first and second methods for producing acircuit component built-in module, the thermosetting resin and theconductive substance are preferably heated at 150° C. to 260° C. forcuring. The heating in this range of temperatures can cure thethermosetting resin without causing damage to the circuit component.

In one embodiment of the first and second methods for producing acircuit component built-in module, the thermosetting resin and theconductive substance are preferably pressed at a pressure of 10 kg/cm²to 200 kg/cm² while being heated for curing. Pressing while heatingprovides a circuit component built-in module having an excellentmechanical strength.

In one embodiment of the first and second methods for producing acircuit component built-in module, the step of forming the first sheetfurther comprises the step of heating the sheet mixture at a temperaturebelow a cure temperature (e.g., a temperature lower than a cure startingtemperature) of the thermosetting resin, thereby eliminating theadhesion of the sheet mixture after the step of forming the mixture intothe sheet. A subsequent process can be facilitated by eliminating theadhesion of the sheet mixture.

In one embodiment of the first and second methods for producing acircuit component built-in module, the step of forming the third sheetby burying the circuit component in the second sheet is preferablyperformed at a temperature below a cure temperature of the thermosettingresin. When the step is performed at a temperature below a curetemperature of the thermosetting resin, the thermosetting resin can besoftened without being cured. This embodiment makes it easy to bury thecircuit component in the second sheet, and also makes it to provide asmooth surface to the circuit component built-in module.

In one embodiment of the first and second methods for producing acircuit component built-in module, the step of mounting the circuitcomponent on the wiring pattern comprises the step of electrically andmechanically connecting the circuit component and the wiring patternwith solder. This embodiment prevents poor connection between thecircuit component and the wiring pattern due to heating that isperformed to cure the thermosetting resin.

In one embodiment of the first and second methods for producing acircuit component built-in module, the step of mounting the activecomponent on the wiring pattern comprises the step of electricallyconnecting a gold bump of the active component and the wiring patternwith a conductive adhesive. The use of a conductive adhesive preventspoor connection or dislocation of components from occurring at asubsequent step of heating.

As described above, the circuit component built-in module of the presentinvention employs the insulating substrate comprising a mixture of aninorganic filler and a thermosetting resin and also utilizes theinner-via-hole connection. This makes it possible to mount circuitcomponents with high density and also allows high heat dissipation.Therefore, the present invention provides a highly reliable circuitcomponent built-in module with circuit components mounted with highdensity.

Furthermore, it is possible to mount circuit components with higherdensity by making the circuit component built-in module of the presentinvention in a multilayered structure.

Furthermore, in the circuit component built-in module of the presentinvention, the heat conductivity, the coefficient of linear expansion,the dielectric constant or the like of the insulating substrate can becontrolled by selecting a suitable inorganic filler. Therefore, in thecircuit component built-in module of the present invention, it ispossible to equalize substantially the coefficient of linear expansionof the insulating substrate with that of the semiconductor device, sothat the present invention is preferably used as a circuit componentbuilt-in module in which a semiconductor device is built-in.Furthermore, the heat conductivity of the insulating substrate can beimproved so that the present invention is preferably used as a circuitcomponent built-in module in which a component that requires heatdissipation such as a semiconductor device is built-in. Furthermore, itis possible to reduce the dielectric constant of the insulatingsubstrate, so that the present invention is preferably used as a circuitcomponent built-in module for high frequency circuits.

According to the methods for producing a circuit component built-inmodule of the present invention, the above-described circuit componentbuilt-in module can be produced easily.

Furthermore, according to the methods for producing a circuit componentbuilt-in module of the present invention, wiring patterns can be buriedin the insulating substrate by using a release film provided with thewiring patterns. Therefore, a circuit component built-in module having asmooth surface can be obtained. Thus, when additional circuit componentsare mounted on the wiring patterns on the surface, a circuit componentbuilt-in module having circuit components mounted with higher densitycan be obtained.

These and other advantages of the present invention will become apparentto those skilled in the art upon reading and understanding the followingdetailed description with reference to the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective cross-sectional view showing one embodiment of acircuit component built-in module of the present invention.

FIGS. 2(a) to 2(h) are views showing a process sequence in an embodimentof a method for producing a circuit component built-in module of thepresent invention.

FIGS. 3(a) to 3(h) are views showing a process sequence in an embodimentof a method for producing a circuit component built-in module of thepresent invention.

FIG. 4 is a perspective cross-sectional view showing an embodiment of acircuit component built-in module of the present invention.

FIGS. 5(a) to 5(h) are views showing a process sequence in an embodimentof a method for producing a circuit component built-in module of thepresent invention.

FIGS. 6(a) to 6(g) are views showing a process sequence in an embodimentof a method for producing a circuit component built-in module of thepresent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, the present invention will be described by way ofembodiments with reference to the accompanying drawings.

Embodiment 1

One example of a circuit component built-in module of the presentinvention will be described with reference to FIG. 1 of Embodiment 1.FIG. 1 is a perspective cross-sectional view of a circuit componentbuilt-in module 100 of this embodiment.

Referring to FIG. 1, the circuit component built-in module 100 inEmbodiment 1 includes an insulating substrate 101, wiring patterns 102aand 102b formed on one principal plane and the other principal plane ofthe insulating substrate 101, circuit components 103 connected to thewiring pattern 102b and arranged in the insulating substrate 101, and aninner via 104 for electric connection between the wiring patterns 102aand 102b.

The insulating substrate 101 is formed of a mixture comprising aninorganic filler and a thermosetting resin. For the inorganic filler,for example, Al₂ O₃, MgO, BN, AlN or SiO₂ can be used. The inorganicfiller is preferably contained in an amount of 70 wt % to 95 wt % on thebasis of the mixture. The average particle diameter of the inorganicfiller is preferably 0.1 μm to 100 μm. Preferable examples of thethermosetting resin include an epoxy resin, a phenol resin or a cyanateresin, which are highly resistant against heat. An epoxy resin is mostpreferable because of its especially high heat resistance. The mixturemay further comprise a dispersant, a coloring agent, a coupling agent ora releasing agent.

The wiring patterns 102a and 102b are formed of an electricallyconductive substance, such as a copper foil or a conductive resincomposition. When a copper foil is used for the wiring pattern, forexample, a copper foil with a thickness of about 18 μm to 35 μm producedby electrolytic plating can be used. The surface of the copper foil thatis in contact with the insulating substrate 101 is preferably made roughso that the adhesion with the insulating substrate 101 can be improved.Furthermore, the copper foil whose surface has been subjected to acoupling treatment or plated with tin, zinc or nickel can be used forbetter adhesion and oxidation resistance. Furthermore, metal lead frameproduced by etching or stamping can be used for the wiring patterns 102aand 102b.

The circuit components 103 include, for example, an active component103a and a passive component 103b. A semiconductor device such as atransistor, an IC, and an LSI can be used for the active component 103a.The semiconductor device may be a semiconductor bare chip. A chipresistor, a chip capacitor or a chip inductor can be used for thepassive component 103b. The circuit components 103 may not include thepassive component 103b.

The active component 103a is connected to the wiring pattern 102a byflip chip bonding. The semiconductor bare chips are flip-chip bonded sothat circuit components can be mounted with high density.

The inner via 104 is formed of a conductive substance. For example, aconductive resin composition comprising metal particles and athermosetting resin can be used for the inner via 104. Examples of themetal particles include gold, silver, copper and nickel. Gold, silver,copper and nickel are preferable because of their high conductivity.Among them, copper is most preferable because of its especially highconductivity and small migration. As for the thermosetting resin, forexample, an epoxy resin, a phenol resin or a cyanate resin can be used.An epoxy resin is most preferable because of its high heat resistance.

In the circuit component built-in module 100 in Embodiment 1, the wiringpatterns 102a and 102b are connected by the inner via 104 filling athrough-hole in the insulating substrate 101. As a result, in thecircuit component built-in module 100, the circuit components 103 can bemounted with high density.

Furthermore, in the circuit component built-in module 100, the inorganicfiller contained in the insulating substrate 101 swiftly conducts theheat generated in the circuit components. Therefore, a highly reliablecircuit component built-in module can be obtained.

Furthermore, in the circuit component built-in module 100, thecoefficient of linear expansion, the heat conductivity, and thedielectric constant of the insulating substrate 101 can be controlledeasily by selecting a suitable organic filler for the insulatingsubstrate 101. A coefficient of linear expansion of the insulatingsubstrate 101 substantially equal to that of the semiconductor deviceprevents cracks or the like from occurring due to a temperature change.As a result, a reliable circuit component built-in module can beobtained. An improvement in the heat conductivity of the insulatingsubstrate 101 allows a reliable circuit component built-in module to beproduced even if the circuit components are mounted with high density. Alow dielectric constant of the insulating substrate 101 allows a modulefor high frequency circuit with little dielectric loss to be produced.

Furthermore, in the circuit component built-in module 100, theinsulating substrate 101 can shield the circuit components 103 from theexternal air, thus preventing deterioration of reliability due tohumidity.

Furthermore, in the circuit component built-in module 100 of the presentinvention, the insulating substrate 101 is formed of a mixture of aninorganic filler and a thermosetting resin, so that the substrate 101can be produced easily without being sintered at a high temperatureunlike a ceramic substrate.

In the circuit component built-in module 100 shown in FIG. 1, the wiringpattern 102a is not buried in the insulating substrate 101. However, thewiring pattern 102a may be buried in the insulating substrate 101 (referto FIG. 3(h)).

In the circuit component built-in module 100 shown in FIG. 1, no circuitcomponent is mounded on the wiring pattern 102a. However, a circuitcomponent may be mounded on the wiring pattern 102a, and the circuitcomponent built-in module may be molded with resin (the same is appliedto the following embodiments). The circuit components can be mountedwith a higher density by mounting circuit components on the wiringpattern 102a.

Embodiment 2

One embodiment of a method for producing the circuit component built-inmodule shown in FIG. 1 will be described with reference to FIGS. 2(a) to2(h) of Embodiment 2. The materials and the circuit components used inEmbodiment 2 are the same as those described in Embodiment 1.

FIGS. 2(a) to 2(h) are cross-sectional views showing a process sequencein one embodiment of a method for producing the circuit componentbuilt-in module.

First, as shown in FIG. 2(a), a mixture of an inorganic filler and athermosetting resin is processed so as to form a mixture 200 in the formof a sheet. An inorganic filler and an uncured thermosetting resin aremixed so as to form a paste mixture. The paste mixture is molded in apredetermined thickness so as to form the mixture 200 in the form of asheet (hereinafter, referred to as "sheet mixture").

The sheet mixture 200 may be heated at a temperature below the curingtemperature of the thermosetting resin. The heat treatment allows theadhesion of the mixture 200 to be eliminated while maintaining theflexibility, thereby facilitating the subsequent processes. In addition,for a mixture comprising a thermosetting resin dissolved in a solvent, aheat treatment serves to remove the solvent partially.

Thereafter, as shown in FIG. 2(b), a through-hole 201 is formed in adesired position in the mixture 200 so as to form a sheet having thethrough-hole 201. The through-hole 201 can be formed by, for example,laser processing or processing with a drill or a mold. Laser processingis preferable because it allows formation of the through-hole 201 in afine pitch and generates no debris. In laser processing, carbon dioxidegas laser or excimer laser is preferably used to facilitate theprocessing. The through-hole 201 may be formed simultaneously when thepaste mixture is molded into the sheet mixture 200.

Thereafter, as shown in FIG. 2(c), a sheet having the through-hole 201filled with a conductive resin composition 202 is formed by filling thethrough-hole 201 with the conductive resin composition 202.

In parallel to the processes shown in FIGS. 2(a) to 2(c), as shown inFIG. 2(d), a circuit component 204 is flip-chip bonded to a copper foil.The circuit component 204 is electrically connected to the copper foil203 via a conductive adhesive 205. As for the conductive adhesive 205,for example, a mixture of a thermosetting resin and gold, silver,copper, or a silver-palladium alloy can be used. Instead of theconductive adhesive 205, a bump produced by a gold wire bonding or asolder bump may be formed on the side of the circuit component 204beforehand, and the gold or the solder may be dissolved by a heattreatment so that the circuit component 204 can be mounted on the copperfoil 203. Furthermore, the solder bump can be used together with theconductive adhesive.

A sealing resin may be injected between the copper foil 203 and thecircuit component 204 mounted on the copper foil 203 (also in thefollowing embodiments, a sealing resin may be injected between a circuitcomponent and a copper foil or a circuit component and a wiringpattern). The injection of a sealing resin prevents the formation ofgaps between the semiconductor device and the wiring pattern whenburying the semiconductor device in the sheet in a subsequent process.An underfill resin, which is used for general flip chip bonding, can beused for the sealing resin.

In parallel to the processes shown in FIGS. 2(a) to 2(c), a copper foil206 is formed, as shown in FIG. 2(e).

Thereafter, as shown in FIG. 2(f), the sheet of FIG. 2(c) is sandwichedbetween the copper foil 203 provided with the circuit component 204 andthe copper foil 206 in a suitable position.

Then, as shown in FIG. 2(g), the sheet together with the copper foils203 and 206 are pressed, so that the circuit component 204 is buried inthe sheet. Then, the sheet is heated so that the thermosetting resin inthe mixture 200 and the conductive resin composition 202 is cured. Thus,the sheet in which the circuit component 204 is buried is formed. Theheating is performed at a temperature equal to or higher than atemperature at which the thermosetting resin in the mixture 200 and theconductive resin composition 202 is cured (e.g., 150° C. to 260° C.).The mixture 200 serves as an insulating substrate 207, and theconductive resin composition 202 serves as an inner via 208. Thisprocess allows the copper foils 203 and 206, the circuit component 204and the insulating substrate 207 to strongly adhere to each othermechanically. The inner via 208 electrically connects the copper foils203 and 206. The mechanical strength of the circuit component module canbe improved by applying a pressure of 10 kg/cm² to 200 kg/cm² whileheating to cure the thermosetting resin in the mixture 200 and theconductive resin composition 202 (the same can apply in the followingembodiments).

Thereafter, as shown in FIG. 2(h), the copper foils 203 and 206 areprocessed into wiring patterns 209 and 210.

Thus, the circuit component built-in module as described in Embodiment 1can be formed. The above-described method allows the circuit componentbuilt-in module as described in Embodiment 1 to be produced easily.

In Embodiment 2, the conductive resin composition 202 is used as aconductive substance with which the through-hole 201 is filled. However,the conductive substance is not limited thereto, and any thermosettingconductive substance can be used, which also applies to the followingembodiments.

Embodiment 3

Another embodiment of a method for producing the circuit componentbuilt-in module shown in FIG. 1 will be described with reference toFIGS. 3(a) to 3(h) of Embodiment 3. The materials and the circuitcomponents used in Embodiment 3 are the same as those described inEmbodiment 1.

FIGS. 3(a) to 3(h) are cross-sectional views showing a process sequencefor producing a circuit component built-in module in Embodiment 3.

First, as shown in FIG. 3(a), a mixture comprising an inorganic fillerand a thermosetting resin is processed into a sheet mixture 300. Sincethis process is the same as that described with reference to FIG. 2(a),it will not be described further herein.

Thereafter, as shown in FIG. 3(b), a through-hole 301 is formed in adesired position of the mixture 300. Since this process is the same asthat described with reference to FIG. 2(b), it will not be describedfurther herein.

Then, as shown in FIG. 3(c), the through-hole 301 is filled with aconductive resin composition 302, so as to form a sheet with thethrough-hole 301 filled with the conductive resin composition 302.

In parallel to the processes shown in FIGS. 3(a) to 3(c), as shown inFIG. 3(d), a wiring pattern 303 is formed on a release film 305, and acircuit component 304 is mounted on the wiring pattern 303. The circuitcomponent 304 is mounted in the same manner as described with referenceto FIG. 2(d), 25 so that it will not be described further herein. Forexample, polyethylene terephthalate or polyphenylene sulfide can be usedfor the release film 305. The wiring pattern 303 can be formed byattaching a copper foil to the release film 305 and then performingphotolithography and etching. Instead, a metal lead frame that is formedby etching or stamping can be used for the wiring pattern 303.

In parallel to the processes shown in FIGS. 3(a) to 3(c), as shown inFIG. 3(e), a wiring pattern 306 is formed on a release film 307. Thewiring pattern 306 can be formed in the same manner as the wiringpattern 303.

Thereafter, as shown in FIG. 3(f), the sheet of FIG. 2(c) is sandwichedbetween the release films 305 and 307 in a suitable position so that thewiring patterns 303 and 306 and the conductive substance 302 areconnected in a desired portion.

Then, as shown in FIG. 3(g), the sheet together with the release films305 and 307 is pressed and heated so that the thermosetting resin in themixture 300 and the conductive resin composition 302 is cured. Thus, thesheet in which the circuit component 304 and the wiring patterns 303 and306 are buried is formed. The heating is performed at a temperatureequal to or higher than a temperature at which the thermosetting resinin the mixture 300 and the conductive resin composition 302 is cured(e.g., 150° C. to 260° C.). The mixture 300 serves as an insulatingsubstrate 308, and the conductive resin composition 302 serves as aninner via 309. The inner via 309 electrically connects the wiringpatterns 303 and 306.

Thereafter, as shown in 3(h), the release film 305 and 307 are peeledfrom the sheet of FIG. 3(g).

Thus, the circuit component built-in module as described in Embodiment 1can be produced. The above-described method makes it easy to produce thecircuit component built-in module as described in Embodiment 1.

In this method, the release film 307 on which the wiring pattern 306 hasbeen formed earlier is used, so that the obtained circuit componentbuilt-in module has a smooth surface as a result of burying the wiringpattern 306 in the insulating substrate 308. The smoothness of thesurface makes it possible to mount the components on the wiring pattern306 with high density and thus to achieve higher density circuitcomponents.

Embodiment 4

One embodiment of a circuit component built-in module having amultilayered structure of the present invention will be described withreference to FIG. 4 of Embodiment 4. FIG. 4 is a perspectivecross-sectional view of a circuit component built-in module 400 of thisembodiment.

Referring to FIG. 4, the circuit component built-in module 400 inEmbodiment 4 includes an insulating substrate 401 comprising insulatingsubstrates 401a, 401b and 401c, wiring patterns 402a, 402b, 402c and402d formed on one principal plane and in the internal portion of theinsulating substrate 401, a circuit component 403 arranged in theinternal portion of the insulating substrate 401 and connected to thewiring patterns 402a, 402b or 402c, and an inner via 404 for electricalconnection between the wiring patterns 402a, 402b, 402c and 402d.

The insulating substrates 401a, 401b and 401c are formed of a mixturecomprising an inorganic filler and a thermosetting resin. For example,Al₂ O₃, MgO, BN, AlN or SiO₂ can be used for the inorganic filler. Theinorganic filler is preferably contained in an amount of 70 wt % to 95wt % on the basis of the mixture. The average particle diameter of theinorganic filler is preferably 0.1 μm to 100 μm. Preferable examples ofthe thermosetting resin include an epoxy resin, a phenol resin, or acyanate resin, which are highly resistant against heat. An epoxy resinis most preferable because of its especially high heat resistance. Themixture may further comprise a dispersant, a coloring agent, a couplingagent or a releasing agent.

The wiring patterns 402a, 402b, 402c and 402d are the same as the wiringpatterns 102a and 102b, which are described in Embodiment 1, and theywill not be described further herein.

The circuit component 403 includes, for example, an active component403a and a passive component 403b. A semiconductor device such as atransistor, an IC, and an LSI can be used for the active component 403a.The semiconductor device may be a semiconductor bare chip. A chipresistor, a chip capacitor or a chip inductor can be used for thepassive component 403b. The circuit component 403 may not include thepassive component 403b.

The active component 403a is connected to the wiring patterns 402a,402b, and 403c, for example, by flip chip bonding. The semiconductorbare chips may be flip-chip bonded so that circuit components can bemounted with high density.

The inner via 404 is formed of a conductive substance. For example, aconductive resin composition comprising metal particles and athermosetting resin can be used for the inner via 404. Examples of themetal particles include gold, silver, copper and nickel. Gold, silver,copper and nickel are preferable because of their high conductivity.Among them, copper is most preferable because of its especially highconductivity and small migration. As for the thermosetting resin, forexample, an epoxy resin, a phenol resin or a cyanate resin can be used.An epoxy resin is most preferable because of its high heat resistance.

In the circuit component built-in module 400 shown in FIG. 4, the wiringpattern 402d is not buried in the insulating substrate 401c. However,the wiring pattern 402d may be buried in the insulating substrate 401c(see to FIG. 6(g)).

Although FIG. 4 shows the circuit component built-in module 400 having athree layered structure, a structure having any number of layers can beformed depending on the design, and the same applies to the followingembodiments.

Embodiment 5

Another embodiment of a method for producing the circuit componentbuilt-in module of Embodiment 4 will be described with reference toFIGS. 5(a) to 5(h) of Embodiment 5. The material and the circuitcomponents used in Embodiment 5 are the same as those described inEmbodiment 4.

FIGS. 5(a) to 5(h) are cross-sectional views showing a process sequencefor producing a circuit component built-in module in this embodiment.

First, as shown in FIG. 5(a), a mixture comprising an inorganic fillerand a thermosetting resin is processed into a sheet mixture 500. Athrough-hole is filled with a conductive resin composition 501, so as toform a sheet with the through-hole filled with the conductive resincomposition 501. Since this process is the same as that described withreference to FIGS. 2(a) to 2(c), it will not be described furtherherein.

On the other hand, a wiring pattern 506 is formed on a release film 503,and an active component 504 and a passive component 505 are mounted onthe wiring pattern 506. This process is the same as that described withreference to FIG. 3(d), so that it will not be described further herein.

Thereafter, the sheet of FIG. 5(a) is positioned and superimposed on therelease film 503, and they are pressed. Then, the release film 503 ispeeled off, so that the sheet in which the wiring pattern 506, theactive component 504 and the passive component 505 are buried is formed,as shown in FIG. 5(b).

In parallel to the processes of FIGS. 5(a) and 5(b), a plurality ofsheets in which the wiring pattern 506 and the circuit components areburied are formed in the same manner as those shown in FIGS. 5(a) and5(b) (see to FIGS. 5(c) and 5(d), and FIGS. 5(e) and 5(f)). The wiringpattern 506 and the circuit components are different from layer to layerin accordance with the design.

Thereafter, as shown in FIG. 5(g), the sheet of FIG. 5(d) is sandwichedbetween the sheets of FIGS. 5(b) and 5(f) in a suitable position. Then,a copper foil 507 is superimposed on a principal plane of the sheet ofFIG. 5(f) in which the wiring pattern is not formed.

Thereafter, the sheets and the copper foil 507 are positioned and placedon one another in the process shown in FIG. 5(g), pressed and heated, sothat a sheet having a multilayered structure can be formed, as shown inFIG. 5(h). The heating is performed at a temperature equal to or higherthan a temperature at which the thermosetting resin in the mixture 500and the conductive resin composition 501 is cured (e.g., 150° C. to 260°C.). The mixture 500 serves as an insulating substrate 508, and theconductive resin composition 501 serves as an inner via 509. Thisprocess allows the circuit components 504 and 505, the copper foil 507and the insulating substrate 508 to strongly adhere mechanically. Theinner via 509 electrically connects the wiring pattern 506 and thecopper foil 507. Then, the copper foil 507 is processed into a wiringpattern 510.

Thus, a circuit component built-in module having a multilayeredstructure can be formed. The above-described method allows a circuitcomponent built-in module having a multilayered structure to be producedeasily.

Embodiment 6

Another embodiment of a method for producing the circuit componentbuilt-in module of Embodiment 4 will be described with reference toFIGS. 6(a) to 6(g) of Embodiment 6. The material and the circuitcomponents used in Embodiment 6 are the same as those described inEmbodiment 4.

FIGS. 6(a) to 6(g) are cross-sectional views showing a process sequencefor producing a circuit component built-in module in this embodiment.

First, as shown in FIG. 6(a), a mixture comprising an inorganic fillerand a thermosetting resin is processed into a sheet mixture 600. Athrough-hole is filled with a conductive resin composition 601, so as toform a sheet with the through-hole filled with the conductive resincomposition 601. Since this process is the same as that described withreference to FIGS. 2(a) to 2(c), it will not be described furtherherein.

On the other hand, a wiring pattern 606 is formed on a release film 603,and an active component 604 and a passive component 605 are mounted onthe wiring pattern 606. This process is the same as that described withreference to FIG. 3(d), so that it will not be described further herein.

Thereafter, the sheet of FIG. 6(a) is positioned and superimposed on therelease film 603, and they are pressed. Then, the release film 603 ispeeled off, so that the sheet in which the wiring pattern 606, theactive component 604 and the passive component 605 are buried is formed,as shown in FIG. 6(b).

In parallel to the processes of FIGS. 6(a) and 6(b), a plurality ofsheets in which the wiring pattern 606 and the circuit components areburied are formed in the same manner as those shown in FIGS. 6(a) and6(b) (refer to FIGS. 6(c) and 6(d)). The wiring pattern 606 and thecircuit components are different from layer to layer in accordance withthe design.

In parallel to the processes of FIGS. 6(a) and 6(b), as shown in FIG.6(e), a wiring pattern 607 is formed on the release film 603.

Thereafter, as shown in FIG. 6(f), the sheet of FIG. 6(d) is positionedand superimposed on the sheet of FIG. 6(b). Then, the release film 603of FIG. 6(e) is superimposed on a principal plane of the sheet of FIG.6(d) on which the wiring pattern 606 is not formed so that the wiringpattern 607 on the release film 603 faces inwards

Thereafter, the sheets and the release film 603 are positioned andattached to each other in the process shown in FIG. 6(f), pressed andheated, so that a sheet having a multilayered structure can be formed,as shown in FIG. 6(g). The heating is performed at a temperature equalto or higher than a temperature at which the thermosetting resin in themixture 600 and the conductive resin composition 601 is cured (e.g.,150° C. to 260° C.). The mixture 600 serves as an insulating substrate608, and the conductive resin composition 601 serves as an inner via609. This process allows the active component 604, the passive component605, the wiring pattern 606 and 607 and the insulating substrate 608 tostrongly adhere mechanically. The inner via 609 electrically connectsthe wiring patterns 606 and 607.

Then, the release film 603 is peeled from the sheet having amultilayered structure, so that a circuit component built-in modulehaving a multilayered structure can be formed.

Thus, the above-described method allows a circuit component built-inmodule having a multilayered structure to be produced easily.

EXAMPLES

Hereinafter, the present invention will be specifically described by wayof examples.

Example 1

In the production of a circuit component built-in module of the presentinvention, an example of a method for producing an insulating substrateformed of a mixture comprising an inorganic filler and a thermosettingresin will be described at first.

In this example, an insulating substrate was produced with a compositionshown in Table 1. Sample 1 in Table 1 is a comparative example.

                                      TABLE 1                                     __________________________________________________________________________                                   Linear          Breakdown                      Sam                                                                              Inorganic filler                                                                      Thermosetting resin                                                                         Heat  expansion                                                                          Dielectric                                                                         Dielectric                                                                          voltage                        ple    amount   amount                                                                            Additive                                                                           conductivity                                                                        coefficient                                                                        constant                                                                           loss  (AC)                           No.                                                                              type                                                                              (wt %)                                                                            type (wt %)                                                                            (wt %)                                                                             (W/mK)                                                                              (ppm/° C.)                                                                  1 MHz                                                                              1 MHz (%)                                                                           kV/mm                          __________________________________________________________________________    1  Al.sub.2 O.sub.3                                                                  60  liquid                                                                             39.8                                                                              carbon                                                                             0.52  45   3.5  0.3   8.1                            2  Al.sub.2 O.sub.3                                                                  70  epoxy                                                                              29.8                                                                              black                                                                              0.87  32   4.7  0.3   10.1                           3  Al.sub.2 O.sub.3                                                                  80  resin                                                                              19.8                                                                              (0.2)                                                                              1.2   26   5.8  0.3   16.5                           4  Al.sub.2 O.sub.3                                                                  85  WE-2025                                                                            14.8     2.8   21   6.1  0.2   15.5                           5  Al.sub.2 O.sub.3                                                                  90       9.8      4.5   16   6.7  0.2   18.7                           6  Al.sub.2 O.sub.3                                                                  95       4.8      5.5   11   7.1  0.2   17.1                           7  MgO 78  liquid                                                                             21.8                                                                              carbon                                                                             4.2   24   8.1  0.4   15.2                           8  BN  77  epoxy                                                                              22.8                                                                              black                                                                              5.5   10   6.8  0.3   17.4                           9  AlN 85  resin                                                                              14.8                                                                              (0.2)                                                                              5.8   18   7.3  0.3   19.3                           10 SiO.sub.2                                                                         75  WE-2025                                                                            24.8     2.2   7    3.5  0.2   18.2                           11 Al.sub.2 O.sub.3                                                                  90  phenol                                                                             9.8 carbon                                                                             4.1   31   7.7  0.5   13.2                                      resin    black                                                                         (0.2)                                                     12 Al.sub.2 O.sub.3                                                                  90  cyanate                                                                            9.8 dispersant                                                                         3.8   15   6.7  0.2   14.5                                      resin    (0.2)                                                     __________________________________________________________________________     Note:                                                                         Liquid epoxy resin: WE2025 manufactured by Nippon Pelnox Corporation          Phenol resin: Fenolight VH4150 manufactured by Dainippon Ink and              Chemicals, Inc.                                                               Cyanate resin: AroCy, M30 manufactured by Asahi Ciba                          Carbon black: P930 manufactured by Toyo Carbon                                Dispersant: Prysurf S208F manufactured by Daiich Kogyo Seiyaku Co., Ltd.      Al.sub.2 O.sub.3 : SA40 manufactured by Showa Denko K.K.                      SiO.sub.2 : primary reagent manufactured by Kanto Chemical Co., Inc.          AlN: manufactured by Dow Chemical Co. Ltd.                                    BN: manufactured by DENKI KAGAKU KOGYO K.K.                                   MgO: primary reagent manufactured by Kanto Chemical Co., Inc.            

In this example, an epoxy resin manufactured by Nippon Pelnox (WE-2025,comprising an acid anhydrous hardening agent) was used for the liquidepoxy resin. A phenol resin manufactured by Dainippon Ink and Chemicals,Inc. (Fenolight, VH-4150) was used for the phenol resin. A cyanate resinmanufactured by Asahi Ciba (AroCy, M-30) was used for the cyanate resin.In this example, carbon black or a dispersant was added as an additive.

A sheet mixture was produced in the following manner. First, apredetermined amount of a paste mixture obtained by mixing thecomponents in the composition shown in Table 1 was poured and spread ona release film. The paste mixture was prepared by mixing an inorganicfiller and a liquid thermosetting resin by an agitator for about 10minutes. The agitator used in this example operates in such a mannerthat an inorganic filler and a liquid thermosetting resin are placed ina container, and the container itself rotates so as to stir the mixturein the container. The mixture obtained by using this agitator isdispersed sufficiently, even if the mixture has a relatively highviscosity. A polyethylene terephthalate film having a thickness of 75 μmwas used for the release film, and the surface of the film was subjectedto a release treatment with silicon.

Next, another release film was placed on the paste mixture on therelease film, and pressing was performed by a pressurizing press so asto form a sheet mixture having a thickness of 500 μm.

Next, the sheet mixture sandwiched between the release films was heatedtogether with the release films under the conditions that allow theelimination of the adhesion of the sheet mixture. The heat treatment wasperformed at 120° C. for 15 minutes. This heat treatment for eliminatingthe adhesion of the sheet mixture facilitates peeling of the releasefilms. The liquid epoxy resin used in this example starts to be cured at130° C., and therefore the epoxy resin was uncured (B stage) under thecondition of this treatment.

Next, the release films were peeled from the sheet mixture, and thesheet mixture was sandwiched between heat resistant release films (PPS:polyphenylene sulfide, a thickness of 75 μm), and heated at atemperature of 170° C. for curing while being pressed at a pressure of50 kg/cm².

Next, the heat resistant release films were peeled from the sheetmixture. Thus, an insulating substance was obtained.

After processing the insulating substrate into a predetermined size, theheat conductivity, the coefficient of linear expansion, the breakdownvoltage, or the like were measured. The breakdown voltage of theinsulating substrate indicates the adhesion between the inorganic fillerand the thermosetting resin that are materials for the insulatingsubstrate. More specifically, when the adhesion between the inorganicfiller and the thermosetting resin is poor, micro gaps therebetween areformed so that the breakdown voltage deteriorates. Such micro gapsdeteriorate the reliability of the circuit component built-in module.The heat conductivity was obtained in the following manner. A surface ofa sample of 10 mm×10 mm was heated in contact with a heater, and anincrease in the temperature on the other surface was measured. The heatconductivity was calculated based on the increase in the temperature onthe other surface. The coefficient of linear expansion was obtained inthe following manner. A change in the size of the insulating substratewas measured when the temperature was raised from room temperature to140° C., and the coefficient of linear expansion was calculated based onthe average value of the change. The breakdown voltage was obtained inthe following manner. A breakdown voltage was calculated when an ACvoltage was applied to the thickness direction of the insulatingsubstrate, and a breakdown voltage per unit thickness was calculated.

As shown in Table 1, when Al₂ O₃ was used for the inorganic filler, theinsulating substrate produced according to the above-described methodhad more than about 10 times the heat conductivity of a conventionalglass-epoxy substrate (0.2 w/mK to 0.3 w/mK). When the content of Al₂ O₃was about 85 wt % or more, the heat conductivity was 2.8 w/mK or more.Al₂ O₃ is also advantageous for reducing cost.

When AlN or MgO was used as the inorganic filler, the conductivity wasas good as or better than that when Al₂ O₃ was used.

When amorphous SiO₂ was used for the inorganic filler, the coefficientof linear expansion became closer to that of a silicon semiconductor (acoefficient of linear expansion of 3×10⁻⁶ /° C.). Therefore, theinsulating substrate comprising amorphous SiO₂ as the inorganic filleris preferably used as a flip chip substrate directly on which asemiconductor is mounted.

Furthermore, when amorphous SiO₂ was used for the inorganic filler, aninsulating substrate having a low dielectric constant was obtained. SiO₂is advantageous in view of its low specific gravity. A circuit componentbuilt-in module comprising SiO₂ as the inorganic filler is preferablyused as a high frequency module such as a cellular phone.

When BN was used for the inorganic filler, an insulating substratehaving a high heat conductivity and a low coefficient of linearexpansion was obtained.

As shown in Table 1, the breakdown voltages of the insulating substratesof all the samples except sample 1 (the comparative example), whichcomprises 60 wt % of Al₂ O₃ as the inorganic filler, were 10 kV/mm ormore. Generally, a breakdown voltage of 10 kV/mm or more can betranslated to mean that the adhesion between the inorganic filler andthe thermosetting resin is good. Therefore, it is preferable that thecontent of the inorganic filler is 70 wt % or more.

Furthermore, when the content of the thermosetting resin is low, thestrength of the insulating substrate is low. Therefore, it is preferablethat the content of the thermosetting resin is 4.8 wy % or more.

Example 2

An illustrative circuit component built-in module produced in the methoddescribed in Embodiment 2 will be described in this example.

The insulating substrate used in this example comprises 90 wt % of Al₂O₃ (S-40 manufactured by Showa Denko K. K., spherical particles, anaverage particle diameter of 12 μm), 9.5 wt % of liquid epoxy resin(EF-450 manufactured by Nippon Rec Co. Ltd.), 0.2 wt % of carbon black(manufactured by Toyo Carbon) and 0.3 wt % of a coupling agent (46B,titanate based coupling agent manufactured by Ajinomoto Co., Inc.).

The materials for the insulating substrate were treated under the sameconditions as those in Example 1, so as to produce a sheet having athickness of 500 μm. The sheet was cut into a predetermined size, andthrough-holes of 0.15 mm diameter for inner-via-hole connection wereformed by using a carbon dioxide gas laser (see FIG. 2(b)).

The through-holes were filled with a conductive resin composition by ascreen printing method (see FIG. 2(c)). The conductive resin compositionwas obtained by mixing 85 wt % of spherical copper particles, 3 wt % ofbisphenol A epoxy resin (Epicoat 828 manufactured by Yuka Shell Epoxy),9 wt % of glycidyl ester based epoxy resin (YD-171 manufactured by TotoKasei), and 3 wt % of amine adduct hardening agent (MY-24 manufacturedby Ajinomoto Co., Inc.).

Next, one surface of a copper foil having a thickness of 35 μm was maderough, and a semiconductor device was flip-chip bonded onto the roughsurface with a conductive adhesive (see FIG. 2(d)).

Then, the sheet with the through-holes filled with the conductive resincomposition was sandwiched between the copper foil provided with asemiconductor device and another separately prepared copper foil havinga thickness of 35 μm (one surface of which was made rough) in a suitableposition (see FIG. 2(f)). The sheet was sandwiched between the copperfoils so that the rough surfaces of the copper foils were in contactwith the sheet.

Then, heating and pressing were performed by a hot-press at atemperature of 120° C. and a pressure of 10 kg/cm² for 5 minutes. Sincethe thermosetting resin in the sheet was softened by heating at atemperature below the curing temperature, the semiconductor device waseasily buried in the sheet.

Then, the heating temperature was raised to 175° C., and heating wasperformed for 60 minutes (see FIG. 2(g)). This heating allowed the epoxy10 resin in the sheet and the epoxy resin in the conductive resincomposition to be cured, so that the semiconductor device and the copperfoils and the sheet were strongly connected mechanically. This heatingalso allowed the conductive resin composition and the copper foils to beconnected electrically (through inner-via connection) and mechanically.

Then, the copper foil on the surface of the sheet in which thesemiconductor device was buried was etched in a photolithography processand an etching process so as to form a wiring pattern (see FIG. 2(h)).Thus, a circuit component built-in module was produced.

In order to evaluate the reliability of the circuit component built-inmodule produced in this example, a solder reflow test and a temperaturecycle test were conducted. The solder reflow test was conducted with abelt type reflow tester, in which a 10 second cycle was repeated 10times at a maximum temperature of 260° C. The temperature cycle test wasconducted by allowing the circuit component built-in module to stand at125° C. for 30 minutes and then at -60° C. for 30 minutes per cycle, andrepeating this cycle for a total of 200 cycles.

In either the solder reflow test or the temperature cycle test, nocracks were generated in the circuit component built-in module in thisexample, and abnormality was not recognized, even if a supersonic flawdetector was used. These tests confirmed that the semiconductor deviceand the insulating substrate adhered to each other tightly. A resistancevalue of the inner-via connection by the conductive resin compositionwas not substantially changed between measurements made before and afterthe tests.

Example 3

An illustrative circuit component built-in module produced in the methoddescribed in Embodiment 3 will be described in this example.

First, a sheet (500 μm thick) having through-holes filled with aconductive resin composition was produced in the same method as that inExample 2 (see FIG. 3(c)).

Next, a copper foil having a thickness of 35 μm was adhered to a releasefilm (formed of polyphenylene sulfide and 150 μm thick) with anadhesive. One surface of the copper foil was rough, and the other smoothsurface of the copper foil was adhered to the release film.

Then, the copper foil on the release film was etched in aphotolithography process and an etching process so as to form a wiringpattern. Furthermore, a semiconductor device was flip-chip bonded ontothe wiring pattern with a solder bump (see FIG. 3(d)).

Then, a sealing resin was injected in a gap between the wiring patternand the semiconductor device on the wiring pattern. More specifically, ahot plate heated to 70° C. was tilted, and the release film having thewiring pattern provided with the semiconductor device was placed on thehot plate. Thereafter, a sealing resin was gradually injected betweenthe semiconductor device and the wiring pattern with an injection. Theinjection of the sealing resin between the semiconductor device and thewiring pattern was completed in about 10 seconds. The hot plate washeated for the purpose of lowering the viscosity of the sealing resin sothat the injection was completed in a short time. The hot plate wastilted for the purpose of facilitating the injection. As for the sealingresin, a product manufactured by Techno alpha Co. Ltd., EL18B, was used.The product, EL18B, is a resin comprising one-component epoxy resinmixed with SiO₂ powders.

On the other hand, in parallel to the above-described process, a releasefilm (formed of polyphenylene sulfide and 150 μm thick) having a wiringpattern formed on one surface thereof was produced (see FIG. 3(e)).

Next, the sheet having the through-holes filled with the conductiveresin composition was sandwiched between the release film with thesemiconductor device bonded thereon and the release film having thewiring pattern on one surface thereof in a suitable position (see FIG.3(f)).

Then, heating and pressing were performed by a hot-press at atemperature of 120° C. and a pressure of 10 kg/cm² for 5 minutes. Sincethe thermosetting resin in the sheet was softened by heating at atemperature below the curing temperature, the semiconductor device andthe wiring pattern were easily buried in the sheet.

Then, the heating temperature was raised to 175° C., and heating wasperformed for 60 minutes (see FIG. 3(g)). This heating allowed the epoxyresin in the sheet and the conductive resin composition to be cured, sothat the semiconductor device and the wiring pattern and sheet werestrongly connected mechanically. This heating also allowed theconductive resin composition and the wiring pattern to be connectedelectrically (through inner-via connection) and mechanically.Furthermore, this heating allowed the sealing resin injected between thesemiconductor device and the wiring pattern to be cured.

Then, the release film was peeled from the sheet (see FIG. 3(h)). Therelease film made of polyphenylene sulfide has a heat resistance againstthe above-mentioned heating temperature or more. Furthermore, the roughsurface of the copper foil was adhered to the sheet and the inner via,and the smooth surface of the copper foil was adhered to the releasefilm. Therefore, the adhesion between the sheet and the inner via andthe copper foil was larger than that between the release film and thecopper foil. This allowed the release film alone to be peeled off. Thus,a circuit component built-in module was produced.

In order to evaluate the reliability of the circuit component built-inmodule produced in this example, a solder reflow test and a temperaturecycle test were conducted under the same conditions as those in Example2.

In either the solder reflow test or the temperature cycle test, nocracks were generated in the circuit component built-in module in thisexample, and abnormality was not recognized, even if a supersonic flawdetector was used.

These tests confirmed that the semiconductor device and the insulatingsubstrate adhered to each other tightly. A resistance value of theinner-via connection by the conductive resin composition was notsubstantially changed between measurements made before and after thetests.

Example 4

An illustrative circuit component built-in module having a multilayeredstructure produced in the method described in Embodiment 5 will bedescribed in this example.

In Example 4, a semiconductor device and a chip component were used asthe circuit components.

First, a sheet having through-holes filled with a conductive resincomposition was formed in the same manner as in Example 2.

Next, the sheet having through-holes filled with a conductive resincomposition was positioned and superimposed on a release film (made ofpolyphenylene sulfide) provided with a wiring pattern having a circuitcomponent flip-chip bonded thereon (see FIG. 5(a)).

Then, heating and pressing were performed by a hot-press at atemperature of 120° C. and a pressure of 10 kg/cm² for 5 minutes. Sincethe thermosetting resin in the sheet was softened by heating at atemperature below the curing temperature, the circuit component waseasily buried in the sheet. Then, the release film was peeled from thesheet so as to form a sheet in which the circuit component was buried(see FIG. 5(b)).

A plurality of sheets were prepared in this manner, and the plurality ofsheets and a copper foil were positioned and superimposed on one another(FIG. 5(g)).

Then, heating and pressing were performed by a hot-press at atemperature of 175° C. and a pressure of 50 kg/cm² for 60 minutes. Thisheating and pressing treatment allowed the copper foil and the pluralityof sheets in which circuit components were buried to be integrated, andthus one sheet was formed. The heating and pressing treatment allowedthe epoxy resin in the sheet and the conductive resin composition to becured, so that the circuit components and the wiring pattern and thesheet were strongly connected mechanically. The heating and pressingtreatment also allowed the copper foil and the wiring pattern and theconductive resin composition to be connected electrically (throughinner-via connection) and mechanically.

Then, the copper foil on the surface of the sheet in which the circuitcomponents were buried was etched in a photolithography process and anetching process so as to form a wiring pattern (see FIG. 5(h)). Thus, acircuit component built-in module having a multilayered structure wasproduced.

In order to evaluate the reliability of the circuit component built-inmodule produced in this example, a solder reflow test and a temperaturecycle test were conducted in the same conditions as in Example 2.

In either the solder reflow test or the temperature cycle test, nocracks were generated in the circuit component built-in module in thisexample, and abnormality was not recognized, even if a supersonic flawdetector was used. These tests confirmed that the semiconductor deviceand the insulating substrate adhered to each other tightly. A resistancevalue of the inner-via connection by the conductive resin compositionwas not substantially changed between measurements made before and afterthe tests.

Example 5

An illustrative circuit component built-in module having a multilayeredstructure produced in the method described in Embodiment 6 will bedescribed in this example.

First, a sheet having through-holes filled with a conductive resincomposition was formed in the same manner as in Example 2. Next, thesheet having through-holes filled with a conductive resin compositionwas positioned and superimposed on a release film (made of polyphenylenesulfide) provided with a wiring pattern having a circuit componentflip-chip bonded thereon (see FIG. 6(a)).

Then, heating and pressing were performed by a hot-press at atemperature of 120° C. and a pressure of 10 kg/cm² for 5 minutes. Sincethe thermosetting resin in the sheet was softened by heating at atemperature below the curing temperature, the circuit component waseasily buried in the sheet. The release film was peeled from the sheetso as to form a sheet (see FIG. 6(b)). Another sheet in which a circuitcomponent was buried was formed in the same manner (see FIG. 6(d)).

Then, wiring patterns were formed on one surface of a release film madeof polyphenylene sulfide (see FIG. 6(e)).

Then, the two sheets with the circuit components buried therein and therelease film provided with the wiring patterns were positioned andsuperimposed on one another (see FIG. 6(f)).

Then, heating and pressing were performed by a hot-press at atemperature of 175° C. and a pressure of 50 kg/cm² for 60 minutes. Thisheating and pressing treatment allowed the release film and theplurality of sheets with the circuit components buried therein to beintegrated, and thus one sheet was formed. The heating and pressingtreatment allowed the epoxy resin in the sheet to be cured, so that thecircuit components and the wiring pattern and the sheet were stronglyconnected mechanically. The heating and pressing treatment also allowedthe epoxy resin in the conductive resin composition to be cured, so thatthe wiring pattern and the conductive resin composition were connectedelectrically (through inner-via connection) and mechanically.

Then, the release film was peeled from the integrated sheet so that acircuit component built-in module having a multilayered structure wasproduced (see FIG. 6(g)).

In order to evaluate the reliability of the circuit component built-inmodule produced in this example, a solder reflow test and a temperaturecycle test were conducted in the same conditions as in Example 2.

In either the solder reflow test or the temperature cycle test, nocracks were generated in the circuit component built-in module in thisexample, and abnormality was not recognized, even if a supersonic flawdetector was used. These tests confirmed that the semiconductor deviceand the insulating substrate adhered to each other tightly. A resistancevalue of the inner-via connection by the conductive resin compositionwas not substantially changed between measurements made before and afterthe tests.

The invention may be embodied in other forms without departing from thespirit or essential characteristics thereof. The embodiments disclosedin this application are to be considered in all respects as illustrativeand not limitative, the scope of the invention is indicated by theappended claims rather than by the foregoing description, and allchanges which come within the meaning and range of equivalency of theclaims are intended to be embraced therein.

What is claimed is:
 1. A circuit component built-in module comprising:aninsulating substrate formed of a mixture comprising 70 wt % to 95 wt %of an inorganic filler and a thermosetting resin; a plurality of wiringpatterns formed on at least a principal plane of the insulatingsubstrate; a circuit component arranged in an internal portion of theinsulating substrate and electrically connected to the wiring patterns;and an inner via formed in the insulating substrate for electricallyconnecting the plurality of wiring patterns.
 2. A circuit componentbuilt-in module according to claim 1, wherein the circuit componentincludes an active component, and the inner via is formed of aconductive resin composition.
 3. A circuit component built-in moduleaccording to claim 1, wherein the wiring patterns are further formed inan internal portion of the insulating substrate.
 4. A circuit componentbuilt-in module according to claim 1, wherein the circuit component isshielded from external air by the insulating substrate.
 5. A circuitcomponent built-in module according to claim 1, wherein thethermosetting resin comprises at least one thermosetting resin selectedfrom the group consisting of an epoxy resin, a phenol resin and acyanate resin.
 6. A circuit component built-in module according to claim1, wherein the inorganic filler comprises at least one inorganic fillerselected from the group consisting of Al₂ O₃, MgO, BN, AlN and SiO₂. 7.A circuit component built-in module according to claim 1, wherein anaverage particle diameter of the inorganic filler is 0.1 μm to 100 μm.8. A circuit component built-in module according to claim 1, wherein thewiring patterns comprise at least one conductive substance selected fromthe group consisting of copper and a conductive resin composition.
 9. Acircuit component built-in module according to claim 1, wherein thewiring patterns comprise lead frames formed by etching or stamping. 10.A circuit component built-in module according to claim 1, wherein thecircuit component comprises at least one component selected from thegroup consisting of a chip resistor, a chip capacitor and a chipinductor.
 11. A circuit component built-in module according to claim 1,wherein the mixture further comprises at least one additive selectedfrom the group consisting of a dispersant, a coloring agent, a couplingagent and a releasing agent.
 12. A circuit component built-in moduleaccording to claim 1, wherein the insulating substrate has a coefficientof linear expansion of 8×10⁻⁶ /° C. to 20×10⁻⁶ /° C. and a heatconductivity of 1 w/mK to 10 w/mK.
 13. A circuit component built-inmodule according to claim 2, wherein the active component comprises asemiconductor bare chip, and the semiconductor bare chip is flip-chipbonded onto the wiring pattern.
 14. A circuit component built-in moduleaccording to claim 2, wherein the conductive resin composition comprisesmetal particles of at least one metal selected from the group consistingof gold, silver, copper and nickel as a conductive component, and anepoxy resin as a resin component.